A liquid crystal display device (display device) including a non-light emission liquid crystal display panel (display panel) is usually equipped also with a back-light unit (illumination device) for supplying light to the liquid crystal display panel. The back-light unit is preferably configured to generate planar light that illuminates the entire area of the planar liquid crystal display panel. Therefore, the back-light unit mounted in the liquid crystal display device may include a light guide plate (light guide member) for mixing light from internal light sources at high degree.
As a back-light unit including a light guide plate, there is known an edge light (side light) type back-light unit, for example. The edge light type back-light unit usually has a structure in which light sources such as light emitting diodes (LEDs) are arranged on a side face of the light guide plate. In the back-light unit having this structure, light emitted from the light sources enters through the side face of the light guide plate to the inside of the light guide plate, and the incident light is guided inside the light guide plate and is emitted to the liquid crystal display panel.
An example of this back-light unit is described in Patent Document 1, for example.